feat(cli): always exit with 0 on cdk diff (under feature flag) (aws#4721

)

* feat(cli): add --no-fail option to diff

Use `cdk diff --no-fail` to exit with 0 even when there is a diff.

To avoid a CLI breaking change, the default remains to fail on diff.

Related to aws#4650 and aws#4708

* use feature flag

packages/@aws-cdk/cx-api/lib/features.ts

@@ -32,4 +32,11 @@ export const DISABLE_METADATA_STACK_TRACE = 'aws:cdk:disable-stack-trace';
  * compatibility, but new projects created using `cdk init` will have this
  * enabled through the generated `cdk.json`.
  */
-export const ENABLE_STACK_NAME_DUPLICATES_CONTEXT = '@aws-cdk/core:enableStackNameDuplicates';
+export const ENABLE_STACK_NAME_DUPLICATES_CONTEXT = '@aws-cdk/core:enableStackNameDuplicates';
+
+/**
+ * IF this is set, `cdk diff` will always exit with 0.
+ *
+ * Use `cdk diff --fail` to exit with 1 if there's a diff.
+ */
+export const ENABLE_DIFF_NO_FAIL = 'aws-cdk:enableDiffNoFail';

packages/@aws-cdk/cx-api/lib/future.ts

@@ -1,4 +1,4 @@
-import { ENABLE_STACK_NAME_DUPLICATES_CONTEXT } from "./features";
+import { ENABLE_DIFF_NO_FAIL, ENABLE_STACK_NAME_DUPLICATES_CONTEXT } from "./features";
 
 /**
  * This map includes context keys and values for feature flags that enable
@@ -14,5 +14,6 @@ import { ENABLE_STACK_NAME_DUPLICATES_CONTEXT } from "./features";
  * Tests must cover the default (disabled) case and the future (enabled) case.
  */
 export const FUTURE_FLAGS = {
-  [ENABLE_STACK_NAME_DUPLICATES_CONTEXT]: 'true'
-};
+  [ENABLE_STACK_NAME_DUPLICATES_CONTEXT]: 'true',
+  [ENABLE_DIFF_NO_FAIL]: 'true',
+};

packages/aws-cdk/bin/cdk.ts

@@ -1,6 +1,7 @@
 #!/usr/bin/env node
 import 'source-map-support/register';
 
+import cxapi = require('@aws-cdk/cx-api');
 import colors = require('colors/safe');
 import path = require('path');
 import yargs = require('yargs');
@@ -72,6 +73,7 @@ async function parseCommandLineArguments() {
       .option('context-lines', { type: 'number', desc: 'Number of context lines to include in arbitrary JSON diff rendering', default: 3, requiresArg: true })
       .option('template', { type: 'string', desc: 'The path to the CloudFormation template to compare with', requiresArg: true })
       .option('strict', { type: 'boolean', desc: 'Do not filter out AWS::CDK::Metadata resources', default: false }))
+      .option('fail', { type: 'boolean', desc: 'Fail with exit code 1 in case of diff', default: false })
     .command('metadata [STACK]', 'Returns all metadata associated with this stack')
     .command('init [TEMPLATE]', 'Create a new, empty CDK project from a template. Invoked without TEMPLATE, the app template will be used.', yargs => yargs
       .option('language', { type: 'string', alias: 'l', desc: 'The language to be used for the new project (default can be configured in ~/.cdk.json)', choices: initTemplateLanuages })
@@ -191,7 +193,8 @@ async function initCommandLine() {
           exclusively: args.exclusively,
           templatePath: args.template,
           strict: args.strict,
-          contextLines: args.contextLines
+          contextLines: args.contextLines,
+          fail: args.fail || !configuration.context.get(cxapi.ENABLE_DIFF_NO_FAIL),
         });
 
       case 'bootstrap':

packages/aws-cdk/lib/cdk-toolkit.ts

@@ -51,7 +51,7 @@ export class CdkToolkit {
     const contextLines = options.contextLines || 3;
     const stream = options.stream || process.stderr;
 
-    let ret = 0;
+    let diffs = 0;
     if (options.templatePath !== undefined) {
       // Compare single stack against fixed template
       if (stacks.length !== 1) {
@@ -62,19 +62,17 @@ export class CdkToolkit {
         throw new Error(`There is no file at ${options.templatePath}`);
       }
       const template = deserializeStructure(await fs.readFile(options.templatePath, { encoding: 'UTF-8' }));
-      ret = printStackDiff(template, stacks[0], strict, contextLines, options.stream);
+      diffs = printStackDiff(template, stacks[0], strict, contextLines, stream);
     } else {
       // Compare N stacks against deployed templates
       for (const stack of stacks) {
         stream.write(format('Stack %s\n', colors.bold(stack.displayName)));
         const currentTemplate = await this.provisioner.readCurrentTemplate(stack);
-        if (printStackDiff(currentTemplate, stack, !!options.strict, options.contextLines || 3, stream) !== 0) {
-          ret = 1;
-        }
+        diffs = printStackDiff(currentTemplate, stack, strict, contextLines, stream);
       }
     }
 
-    return ret;
+    return diffs && options.fail ? 1 : 0;
   }
 
   public async deploy(options: DeployOptions) {
@@ -244,6 +242,13 @@ export interface DiffOptions {
    * @default stderr
    */
   stream?: NodeJS.WritableStream;
+
+  /**
+   * Whether to fail with exit code 1 in case of diff
+   *
+   * @default false
+   */
+  fail?: boolean;
 }
 
 export interface DeployOptions {

packages/aws-cdk/test/integ/cli/app/cdk.json

@@ -1,4 +1,7 @@
 {
   "app": "node app.js",
-  "versionReporting": false
+  "versionReporting": false,
+  "context": {
+    "aws-cdk:enableDiffNoFail": "true"
+  }
 }

packages/aws-cdk/test/integ/cli/test-cdk-diff.sh

@@ -6,11 +6,14 @@ source ${scriptdir}/common.bash
 
 setup
 
-function cdk_diff() {
-    cdk diff $1 2>&1 || true
-}
+cdk diff ${STACK_NAME_PREFIX}-test-1 2>&1 | grep "AWS::SNS::Topic"
+cdk diff ${STACK_NAME_PREFIX}-test-2 2>&1 | grep "AWS::SNS::Topic"
 
-cdk_diff ${STACK_NAME_PREFIX}-test-1 | grep "AWS::SNS::Topic"
-cdk_diff ${STACK_NAME_PREFIX}-test-2 | grep "AWS::SNS::Topic"
+failed=0
+cdk diff --fail ${STACK_NAME_PREFIX}-test-1 2>&1 || failed=1
+
+if [ $failed -ne 1 ]; then
+  fail 'cdk diff with --fail does not fail'
+fi
 
 echo "✅  success"

packages/aws-cdk/test/integ/cli/test-cdk-iam-diff.sh

@@ -7,7 +7,7 @@ source ${scriptdir}/common.bash
 setup
 
 function nonfailing_diff() {
-    ( cdk diff $1 2>&1 || true ) | strip_color_codes
+    cdk diff $1 2>&1 | strip_color_codes
 }
 
 assert "nonfailing_diff ${STACK_NAME_PREFIX}-iam-test" <<HERE

packages/aws-cdk/test/test.diff.ts

@@ -53,6 +53,32 @@ export = {
     test.ok(plainTextOutput.indexOf('Stack A') > -1, `Did not contain "Stack A": ${plainTextOutput}`);
     test.ok(plainTextOutput.indexOf('Stack B') > -1, `Did not contain "Stack B": ${plainTextOutput}`);
 
+    test.equals(0, exitCode);
+
+    test.done();
+  },
+
+  async 'exits with 1 with diffs and fail set to true'(test: Test) {
+    // GIVEN
+    const provisioner: IDeploymentTarget = {
+      async readCurrentTemplate(_stack: cxapi.CloudFormationStackArtifact): Promise<Template> {
+        return {};
+      },
+      async deployStack(_options: DeployStackOptions): Promise<DeployStackResult> {
+        return { noOp: true, outputs: {}, stackArn: ''};
+      }
+    };
+    const toolkit = new CdkToolkit({ appStacks, provisioner });
+    const buffer = new StringWritable();
+
+    // WHEN
+    const exitCode = await toolkit.diff({
+      stackNames: ['A'],
+      stream: buffer,
+      fail: true
+    });
+
+    // THEN
     test.equals(1, exitCode);
 
     test.done();